Multi-spark ignition system for internal combustion engines

Abstract

To generate a plurality of spark pulses for a multi-spark breakdown for each ignition event for ignition of a combustible mixture in an internal combustion engine, while providing for positive generation of the first spark at a predetermined time instant, a time delay circuit is connected to control a frequency generator for generation of a plurality of spark pulses, the first spark pulse, however, being controlled through a differentiating network, for example an R/C network, for positive generation of the first pulse.

We claim: 
     
       1. In a sequential multiple spark pulse ignition system having an ignition coil (20) and at least one spark gap (21) connected to the secondary of the coil (20);   a controlled switch (16) connected to the primary of the coil and controlling current flow therethrough;   means (10, 11, 12) furnishing a signal (B) controlling generation of an ignition event;   and means to separately control the closing and opening of said controlled switch (16) for generation of the first spark pulse of said sequential multiple spark pulses and the next subsequent spark pulses comprising   a circuit stage (13) including a R/C function network connected to and controlling said controlled switch (16) to control supply of current to the coil to store energy for a first spark pulse;   a frequency generator (17) controlling repetitive opening and closing of the controlled switch (16) for an ignition event to generate said sequential spark pulses upon opening, after prior closing, of said controlled switch;   and a time delay circuit (14), serially connected to the frequency generator (17), the series circuit formed by the time delay circuit (14) and the frequency generator (17) being connected in parallel to the circuit stage (13), said circuit stage (13) providing a control pulse to the controlled switch (16) upon sensing an ignition event signal from said signal furnishing means (10, 11, 12) and said time delay circuit initiating a timing interval and after elapse thereof, controlling application of pulses from the frequency generator to the controlled switch (16).   
     
     
       2. System according to claim 1, wherein the differentiating circuit (13) has a long decay time to provide for a first pulse to the controlled switch of extended duration. 
     
     
       3. System according to claim 1, wherein the circuit stage (13) provides an output pulse having the characteristics of an extended sawtooth wave to provide a first pulse to the controlled switch (16) of extended duration. 
     
     
       4. System according to claim 1, wherein the differentiating circuit (13) is an R/C circuit. 
     
     
       5. System according to claim 1, further comprising a wave shaping stage (15) connected in advance of the controlled switch (16). 
     
     
       6. System according to claim 5, wherein the circuit stage (13) is an R/C circuit. 
     
     
       7. System according to claim 7, wherein the wave shaping stage (15) is a Schmitt trigger. 
     
     
       8. System according to claim 1, wherein the circuit stage (13) has a storage time constant which is long with respect to the pulses from the pulse generator (17) to provide for a first pulse to the controlled switch (16) of extended duration. 
     
     
       9. System according to claim 1, wherein the circuit stage (13) comprises a differentiating circuit. 
     
     
       10. System according to claim 8, wherein the wave shaping stage senses voltage levels upon rise and fall of said first pulse provided by the electromagnetic energy storage control circuit. 
     
     
       11. System according to claim 8, wherein the circuit stage (13) is an R/C circuit having a long time constant, and the wave shaping stage (15) senses voltage levels upon rise and fall of the first pulse provided by the R/C circuit.